content: /*
   * Copyright 2016-2020 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.interop;
  
  /**
   * Convert a V1 Single into a V3 Maybe, composing cancellation.
   *
   * @param <T> the value type
   */
  final class SingleV1ToMaybeV3<T> extends io.reactivex.rxjava3.core.Maybe<T> {
  
      final rx.Single<T> source;
  
      SingleV1ToMaybeV3(rx.Single<T> source) {
          this.source = source;
      }
  
      @Override
      protected void subscribeActual(io.reactivex.rxjava3.core.MaybeObserver<? super T> observer) {
          SourceSingleSubscriber<T> parent = new SourceSingleSubscriber<>(observer);
          observer.onSubscribe(parent);
          source.subscribe(parent);
      }
  
      static final class SourceSingleSubscriber<T> extends rx.SingleSubscriber<T>
      implements io.reactivex.rxjava3.disposables.Disposable {
  
          final io.reactivex.rxjava3.core.MaybeObserver<? super T> observer;
  
          SourceSingleSubscriber(io.reactivex.rxjava3.core.MaybeObserver<? super T> observer) {
              this.observer = observer;
          }
  
          @Override
          public void onSuccess(T value) {
              if (value == null) {
                  observer.onError(new NullPointerException(
                          "The upstream 1.x Single signalled a null value which is not supported in 3.x"));
              } else {
                  observer.onSuccess(value);
              }
          }
  
          @Override
          public void onError(Throwable error) {
              observer.onError(error);
          }
  
          @Override
          public void dispose() {
              unsubscribe();
          }
  
          @Override
          public boolean isDisposed() {
              return isUnsubscribed();
          }
      }
  }
  